1. Field of the Invention
This invention relates to a wet process of manufacturing mineral-fiberboard products, and is concerned more particularly with the production of a mineral fiber acoustical board having a fine-textured appearance.
2. Description of the Prior Art
Acoustical boards which have high sound-absorption properties can be made from a water slurry of mineral wool fibers and a binder such as starch. In the manufacture of a desirable type of such boards, the mineral wool is introduced to the slurry in the form of pellets of nodulated mineral wool. A mat is then formed by continuously depositing the slurry upon a moving wire screen and removing the water by drainage and suction. The mat thus formed is dried and the binder set, after which the mat is cut into units of desired dimensions. The product may be provided with fissures or perforations or otherwise textured in order to improve its appearance and enhance its sound-absorption properties. Use of the nodulated mineral wool contributes to an especially attractive appearance in the finished product and also improves the porosity of the product, enabling it to absorb sound more readily.
A disadvantage of the above water-laid technique is that it requires the pre-nodulation of the mineral wool and thus entails an additional process step. Also, various conventional methods of nodulating or granulating mineral wool unfortunately result in breakage of fibers, which diminishes the quality of the wool.
It would be desirable to provide a mineral fiberboard product which would have a combination of advantageous physical properties, including a highly decorative and pleasing appearance, by a wet-forming technique which would be relatively simple and economical and not require extra manufacturing steps, such as a pre-nodulation of mineral fibers.